Maximum likelihood detection for quantized MIMO systems
ABSTRACT In this work, maximum likelihood-detection (ML-detection) for MIMO systems operating on quantized data is considered. It turns out that the optimal decision rule is generally intractable. Therefore, we propose a suboptimal solution with lower complexity. Assuming a Rayleigh fading MIMO environment, an upper bound on the error probability is derived for the case where the number of transmit and receive antennas are equal. Furthermore, we introduce a new performance measure that relates the outage properties to the bit resolution in this context.
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ABSTRACT: Studies the asymptotic characteristics of uniform scalar quantizers that are optimal with respect to mean-squared error (MSE). When a symmetric source density with infinite support is sufficiently well behaved, the optimal step size Δ<sub>N</sub> for symmetric uniform scalar quantization decreases as 2σN<sup>-1</sup>V¯ <sup>-1</sup>(1/6N<sup>2</sup>), where N is the number of quantization levels, σ<sup>2</sup> is the source variance and V¯<sup>-1 </sup>(·) is the inverse of V¯(y)=y<sup>-1</sup> ∫<sub>y </sub><sup>∞</sup> P(σ<sup>-1</sup>X>x) dx. Equivalently, the optimal support length NΔ<sub>N</sub> increases as 2σV¯<sup>-1</sup>(1/6N<sup>2</sup>). Granular distortion is asymptotically well approximated by Δ<sub>N</sub><sup>2</sup>/12, and the ratio of overload to granular distortion converges to a function of the limit τ≡lim<sub>y→∞</sub>y<sup>-1</sup>E[X|X>y], provided, as usually happens, that τ exists. When it does, its value is related to the number of finite moments of the source density, an asymptotic formula for the overall distortion D<sub>N</sub> is obtained, and τ=1 is both necessary and sufficient for the overall distortion to be asymptotically well approximated by Δ<sub>N</sub><sup>2</sup>/12. Applying these results to the class of two-sided densities of the form b|x|<sup>β</sup>e(-α|x| <sup>α</sup>), which includes Gaussian, Laplacian, Gamma, and generalized Gaussian, it is found that τ=1, that Δ<sub>N</sub> decreases as (ln N)<sup>1</sup>α//N, that D<sub>N</sub> is asymptotically well approximated by Δ<sub>N</sub><sup>2</sup>/12 and decreases as (ln N)<sup>2</sup>α//N<sup>2</sup>, and that more accurate approximations to Δ<sub>N</sub> are possible. The results also apply to densities with one-sided infinite support, such as Rayleigh and Weibull, and to densities whose tails are asymptotically similar to those previously mentionedIEEE Transactions on Information Theory 04/2001; · 2.62 Impact Factor
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ABSTRACT: Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1989. Includes bibliographical references (leaves 97-100) and index. by Alan Edelman. Ph.D.01/1989;
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ABSTRACT: Multiple antennas can be used for increasing the amount of diversity or the number of degrees of freedom in wireless communication systems. In this paper, we propose the point of view that both types of gains can be simultaneously obtained for a given multiple antenna channel, but there is a fundamental tradeoff between how much of each any coding scheme can get. We give a simple characterization of the optimal tradeoff curve and use it to evaluate the performance of existing multiple antenna schemes.IEEE Transactions on Information Theory 03/2002; · 2.62 Impact Factor